Conventionally, a terminal box that constitutes an output part of a solar cell module and has the following structure has been known (see Patent Document 1). That is, a box body for housing an electrical circuit formed of a terminal block, a bypass diode, and the like is made of weather-resistant resin and is formed into a pan shape with an open side facing an attachment surface (a bottom plate) thereof. In the box body, an area for housing a charging member of the electrical circuit is defined at a position separated from outer plates of the box body. The open surface of the pan shape is covered by a double-layered cover formed of an inner cover made of metallic material and an outer cover made of weather-resistant resin. The area where the charging member of the electrical circuit is housed is filled with highly flame-resistant filler (e.g., two-component mixing type silicone potting material according to Underwriters Laboratories (UL) 94 standard V-0 rating), so that the inner cover is brought close contact with the filler.    Patent Document 1: Japanese Patent Application Laid-open No. 2005-019833